Activity for erista

I need some advice on the best type of plus size shape wear for a ballgown with an open back. (The back has beautiful lace detail- see picture) When I initially tried on the gown I had a bustier-type corset on, but it did show quite a bit from the...

I love these 2 dresses that I tried on today, but they are both so different- I'm not sure which one to go with. Thoughts?